Immunity https://doi.org/10.1016/j.immuni.2018.05.004 (2018)

Diabetes is often accompanied by hypertension, augmented activation of the sympathetic nervous system (SNS) and inflammation. In Immunity, Dutta and colleagues identify a link between SNS signaling and increased splenic myelopoiesis. Diabetic mice show enhanced splenic myelopoiesis; this results from greater SNS activity and production of catecholamines, which act on granulocyte-macrophage progenitors. Sympathetic nerves signal via neuropeptides to tyrosine hydroxylase–expressing leukocytes. Granulocyte-macrophage progenitors proliferate and differentiate in response to SNS signals, whereas ablation of tyrosine hydroxylase–positive cells, blockade of β2-adrenergic receptors or splenic sympathectomy normalizes the number of myeloid cells in diabetic mice. These findings reveal that neuroimmunological signaling within the spleen results in increased ‘emergency’ myelopoiesis.